Fireproofing wood



AT an anion.

HOWARD FREDERICK WEISS, OF MADISON, WISCONSIN, ASSIGNOR TOGuF. BURGESS LABORATORIES, A CORPORATION OF WISCONSIN.

FIREPROOFIN'G WOOD.

No Drawing.

To all whom it may concern:

Be it known that I, HOWARD F. WEISS, a citizen of the United States, residing at Madison, in the county of Dane, State of Wisconsin, have invented certain new and useful Improvements in Fireproofing Wood;

and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a method of rendering wood and similar fibrous material fireproof by depositing an insoluble salt in the 'fibers of the material, and has for its primary object the provision of a'method whereby the fireproofing operation is facilitated and rendered less expensive without detracting from the quality of the product resulting from the operation.

It has heretofore been suggested to impregnate fibrous materials with insoluble borates by first saturating the material with a soluble borate, then drying'the material and finally saturating it with a soluble salt of lead. Only a relatively small amount of insoluble borate is thus precipitated in the fibers, and in order to accomplish the desired result it has been necessary to use a relatively large quantity of the chemicals employed, the greater proportion of which remains in the product, when dried, in a form' ineffective to accomplish the desired result of fireproofing the material. This ineffective filling adds greatly to the weight of the product, thereby increasing the shipping charges thereon.

Furthermore, the formation in the fibers of an insoluble borate, by injecting into the wood a solution of a soluble compound .of boric acid followed by a second injection of a soluble metallic salt, produces an indefinite yield of insoluble borate, which is the essential fire proofing agent in sucha treatment. I have discovered that the yield of in soluble borate may be greatly augmented by rendering the solution of soluble borate somewhat strongly alkaline preferably before it is applied to the fibrous material. I have also discovered that it is unnecessary to thoroughly dry the material between the Specification of Letters Patent.

Application filed January 23, 1919. Serial No. 272,643.

steps of saturating with the soluble borate and with the precipitating agent. The method is particularly applicable to the fireproofing of shingles, clapboards and the like building material, exposed to the weather.

By following the method as hereinafter described, the yield of insoluble borate is greatly increased with a given quantity of chemicals and accordingly the amount of chemicals employed may be reduced to a considerable extent, thus rendering the process less expensive and also lowering the shipping weight of the product.

In carrying out the method I preferably treat the material in a closed cylinder or other suitable apparatus to which a vacuum or pressure may be applied at will. The material in such apparatus is first subjected to a vacuum to withdraw the air therefrom and is then, Without breaking the vacuum, treated with a solution containing preferably 6% or over of a soluble borate to which a proportion of a suitable alkali, for exam ple sodium hydrate, sodium carbonate, potassium hydrate, or potassium carbonate has been added. The exact proportions of the borate and alkali may be varied, suitable- As soon as the material is saturated to a sufiicient extent the solution is removed and the material is again subjected to a vacuum. Without breaking the vacuum I admit the precipitating reagent, which may be a solution of any soluble salt capable of reacting with the soluble borate to precipitate an insoluble borate in the fibers of the material. Various reagents may be employed, as for example, zinc chlorid, magnesium sulfate, and ferric and ferrous sulfate. I prefer I then apply a pressure of ms. esium sulfate. because of its cheapnem an the excellent results that can be secured with it. The precipitating reagent-is subjected to a pressure of about 100-150 pounds per s uare inch. andthe treatment 15 continue for a suitable period, for example, 240 minutes, the solution being maintained at a temgerature in the neighborhood of 90 These factors are determined by degrees the particular character of the material being treated. When the treatment has been completed the excess solution is withdrawn and the material is removed.

As will be readilg understood, the method as hereinbefore continuous until the completion thereo there being no necessity ior intermediate drying of the material. I find that the efiiciency of the method, owing .to the presence ofthe excess of alkali, is increased at least 10% in the precipitation of insoluble borates over the bestresults obtainable where a soluble borate alone is used without the alkali. The final product, owin to the employment of smaller quantities o chemicals, contains a lower proportion of inefiec- 'ing cylinder -or an proves the appearance-of the product and reduces its tendency to corrode nails and similar metal articles with which it comes in contact, the soluble chlorids and sulfates which have a deteriorating action on metals being removed by the washing.

While I have described the method as carried out in an apparatus in which a vacuum and pressure may be employed, it is to be understood that my invention is in no way limited to any particular type of apparatus, it being possible to secure entirely satisfactory results by saturating the material with the respective solutions in open tanks and without employing either vacuum or pressure. The method is of course facilitated and the time required is considerably .de- Y creased by employing a vacuum and pressure where apparatus for this purpose is readily available. I

It is. to be understood that various changes may be made in the details of the method as hereinbefore described and that various equivalent chemicals may be substituted within thescope of the appended claims, without departing from the s irit of the invention or sacrificing any 0 its material advantages.

terial which comprises impregnatin "material with an aqueous borate so ution containing an excess of sodium hydrate,

, efined is substantially I claim:

1. A method of fire proofing fibrous ma-- terial which comprises imgregnatin 'the' material with an aqueous orateso ution .containing'an excess of alkali, and'then impregnating: the material with a solution of'a reagent capable of reacting with the first solution to precipitate an insoluble borate in said material. l 2. A'method of fire proofing fibrous mathe and then impregnatin the materialwith a solution ofa metal sa t capable of reacting with the firsts'olution to precipitate an. insoluble borate in said material.

3.. A method of fire proofing fibrous material which comprises .impregnatin the material with an aqueous borate so ution containing an excess of alkali, and then impregnating the material with a solution of magnesium salt capable of reacting with the first solution to precipitate an insoluble borate in said material,

4. A method of fireproofing fibrous material which comprises impregnating the material with a-solution of a soluble compound of boric acid and a soluble alkali withdrawing the unabsorbed solution an impregnating the materialwith a reagent capab e of reacting with said solution to precipitate an insolublecompound of boric acid in said material.

5. A method of fireproofing terial which comprises impregnating the material under pressure with a solution of fibrous ma-- a soluble compound of boric acid and a soluble alkali, withdrawing the unabsorbed solution and impregnating the materialunder pressure. with a reagent capable of reacting with said solution to precipitate an insoluble compound of boric acid in said material. V o

6. A method of fireproofing fibrous material which comprises impregnating the material with a-solution of'a soluble compound of boric acid and subjectin the ma-' terial while still in a moist conditlon to the action of a reagent capable of reacting with the soluble boric acid compound to recipitate an insoluble compound thereog 7 A method of fireproofing fibrous material which comprises subjecting the ma-.

terial under pressure to a solution containing a soluble compound of boric acid, removing the excess of such solution, and subjecting the material under pressure and while still in a moist condition to the action of areagent capable of reacting withthe soluble boric acid compound toprecipitate an insoluble compound thereof. 4

8; A method of fireproofing fibrous material which comprises subjecting the masaid solution to form an insoluble compound of boric acid, to impregnate the material under pressure While the material is still in a moist condition, and finally re- 1e moving the excess of said reagent.

In testimony whereof I afiix my signature.

HOWARD FREDERICK WEISS. 

